Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem
Antarctic Ocean and Sea Ice Response to Ozone Depletion: A Two-Time-Scale Problem
复制标题
DOI：
10.1175/jcli-d-14-00313.1
复制
发表时间：
2015-02-01
影响因子：
4.9
通讯作者：
Plumb, Alan
中科院分区：
文献类型：
--
作者：
Ferreira, David;Marshall, John;Plumb, Alan
在两个耦合的气候模式中研究了南大洋对臭氧损失的重复季节性循环的反应，发现包括快速和缓慢的过程。这种快速响应类似于夏季臭氧空洞强迫投射到海表温度（SST）上的南环模态（SAM）的年际特征。它包括增强的向北Ekman漂移，诱导南极洲周围的负夏季SST异常，第二个冬天的海冰冻结提前，以及海冰边缘全年向北扩展。然而，增强的向北Ekman漂移，导致温暖的沃茨从下面的季节性海冰区域的混合层涌上。随着臭氧空洞减少引起的西风持续爆发，这种来自下方的变暖最终超过了异常埃克曼漂移造成的冷却。由此产生的缓慢的时间尺度反应（几年到几十年）导致南极洲周围的SST变暖，最终导致海冰覆盖全年减少。这两个时间尺度的行为，快速冷却，然后缓慢但持续的变暖，是发现在两个耦合模型分析：一个与理想化的几何形状和其他复杂的全球气候模型与现实的几何形状。控制从冷却到变暖的过渡的时间尺度和它们的不确定性的过程进行了描述。最后，这些结果的影响进行了讨论，合理化以前的研究臭氧洞对SST和海冰范围的影响。
The response of the Southern Ocean to a repeating seasonal cycle of ozone loss is studied in two coupled climate models and is found to comprise both fast and slow processes. The fast response is similar to the interannual signature of the southern annular mode (SAM) on sea surface temperature (SST), onto which the ozone hole forcing projects in the summer. It comprises enhanced northward Ekman drift, inducing negative summertime SST anomalies around Antarctica, earlier sea ice freeze-up the following winter, and northward expansion of the sea ice edge year-round. The enhanced northward Ekman drift, however, results in upwelling of warm waters from below the mixed layer in the region of seasonal sea ice. With sustained bursts of westerly winds induced by ozone hole depletion, this warming from below eventually dominates over the cooling from anomalous Ekman drift. The resulting slow time-scale response (years to decades) leads to warming of SSTs around Antarctica and ultimately a reduction in sea ice cover year-round. This two-time-scale behavior-rapid cooling followed by slow but persistent warming-is found in the two coupled models analyzed: one with an idealized geometry and the other with a complex global climate model with realistic geometry. Processes that control the time scale of the transition from cooling to warming and their uncertainties are described. Finally the implications of these results are discussed for rationalizing previous studies of the effect of the ozone hole on SST and sea ice extent.